DESCRIPTION: Muscarinic receptors are key participants in many physiological processes including cognition and memory. Preliminary data indicate that genes encoding the different muscarinic receptor subtypes can be differentially regulated. In the clonal PC12 cell line, m4 receptor mRNAs are stabilized and up-regulated by treatment with NGF. A better understanding of this phenomenon may be relevant to understanding the basis of m4 receptor upregulation in Alzheimer's disease. Both pharmacological and molecular approaches will be employed in these studies. The specific aims are: 1. To identify the signal transduction pathways modulating m4 receptor mRNA stability. The effects on m4 receptor mRNA stability by pharmacological and genetic manipulation of key proteins in the signal transduction pathway of NGF receptor will be studies. 2. To characterize the 3'-untranslated region and flanking nucleotides sequences regulating changes in m4 receptor mRNA stability. Deletion of chimeric cDNA constructs of the m4 receptor mRNA will be generated and transfected into PC12 clonal cell line to localize cis-acting elements controlling transcript stability. 3. To characterize trans-acting factors involved in modifying m4 receptor mRNA stability. This section will focus on detecting and characterizing interactions between m4 receptor mRNA and the regulatory trans-acting protein factors.